Bearing configuration for a rotational equipment assembly

Abstract

An assembly for rotational equipment includes a shaft, a first rolling-element bearing, a second rolling-element bearing, and a mid-shaft foil bearing. The shaft extends along a rotational axis between and to a first axial end and a second axial end. The shaft is configured for rotation about the rotational axis. The first rolling-element bearing is disposed at the first axial end. The second rolling-element bearing is disposed at the second axial end. The mid-shaft foil bearing is disposed axially between the first rolling-element bearing and the second rolling-element bearing.

What is claimed is: 
     
       1. A gas turbine engine for an aircraft propulsion system, the gas turbine engine comprising:
 a bladed compressor rotor and a bladed turbine rotor; 
 a combustor section disposed axially between the bladed compressor rotor and the bladed turbine rotor, the combustor section including a combustor and a diffuser case, the diffuser case disposed between the bladed compressor rotor and the combustor, 
 a shaft extending along a rotational axis between and to a first axial end and a second axial end, the shaft configured for rotation about the rotational axis, and wherein the shaft interconnects the bladed compressor rotor and the bladed turbine rotor; 
 a first rolling-element bearing disposed axially forward of the bladed compressor rotor; 
 a second rolling-element bearing disposed axially aft of the bladed turbine rotor; and 
 a mid-shaft foil bearing disposed axially between the bladed compressor rotor and the bladed turbine rotor, wherein the mid-shaft foil bearing is mounted to the diffuser case. 
 
     
     
       2. The gas turbine engine of  claim 1 , wherein the mid-shaft foil bearing includes a top foil, a bump foil, and a housing, the top foil circumscribes the shaft, the bump foil circumscribes the top foil, and the housing circumscribes the bump foil. 
     
     
       3. The gas turbine engine of  claim 1 , wherein the first rolling-element bearing is disposed at the first axial end. 
     
     
       4. The gas turbine engine of  claim 1 , wherein the second rolling-element bearing is disposed at the second axial end. 
     
     
       5. The gas turbine engine of  claim 1 , wherein the shaft has a first diameter at the first axial end, a second diameter at the second axial end, and a third diameter at the mid-shaft foil bearing, and the third diameter is greater than the first diameter and the second diameter. 
     
     
       6. The gas turbine engine of  claim 1 , further comprising a bladed fan rotor, the shaft interconnects the bladed fan rotor with the bladed compressor rotor and the bladed turbine rotor, and the first rolling-element bearing is disposed axially forward of the bladed fan rotor. 
     
     
       7. A gas turbine engine for an aircraft propulsion system, the gas turbine engine comprising:
 a bladed compressor rotor and a bladed turbine rotor; 
 a combustor section disposed axially between the bladed compressor rotor and the bladed turbine rotor, the combustor section including a combustor and a diffuser case, the diffuser case disposed between the bladed compressor rotor and the combustor; 
 a shaft extending along a rotational axis between and to a first axial end and a second axial end, the shaft configured for rotation about the rotational axis, and the shaft interconnecting the bladed compressor rotor and the bladed turbine rotor; 
 a first liquid-lubricated bearing disposed at the first axial end; 
 a second liquid-lubricated bearing disposed at the second axial end; and 
 an unlubricated mid-shaft foil bearing disposed axially between the bladed compressor rotor and the bladed turbine rotor, wherein the mid-shaft foil bearing is mounted to the diffuser case. 
 
     
     
       8. The gas turbine engine of  claim 7 , wherein the mid-shaft foil bearing includes a top foil, a bump foil, and a housing, the top foil circumscribes the shaft, the bump foil circumscribes the top foil, and the housing circumscribes the bump foil. 
     
     
       9. The gas turbine engine of  claim 7 , wherein the shaft has a first diameter at the first axial end, a second diameter at the second axial end, and a third diameter at the mid-shaft foil bearing, and the third diameter is greater than the first diameter and the second diameter. 
     
     
       10. The gas turbine engine of  claim 7 , wherein each of the first liquid-lubricated bearing and the second liquid-lubricated bearing is a rolling-element bearing. 
     
     
       11. The gas turbine engine of  claim 7 , further comprising a bladed fan rotor, wherein the shaft interconnects the bladed fan rotor with the bladed compressor rotor and the bladed turbine rotor, and the first liquid-lubricated bearing is disposed axially forward of the bladed fan rotor.